Electromagnetic switch



D. A. CHRISTIAN 1,900,912

ELECTROMAGNETIC SWITCH Filed Sept. 19, 1931 March 14, 1933.

2 Shets-Sheet 1 March 1 1933- D. A. CHRISTIAN ELECTROMAGNETIC SWITCH Filed Sept. 19, 1951 2 Sheets-Sheet 2 Patented Mar. 14, 1933 UNITED STATES PATENT OFFICE DAVID ADAM CHRISTIAN, OF LONDON, ENGLAND, ASSIGNOB T0 SIEMENS BROTHERS &

. COMPANY LIMITED, OF LONDON, ENGLAND ELECTROMAGNETIC SWITCH Application filed September 19, 1931, Serial No. 563,875, and in Great Britainseptember 23, 1930.

The resent invention relates to electromagnetic stepping switches and more particularly to groups of such switches having common operating means. I

In systems that are already known, the wipers of theindividual switches arebrought under the influence of a continuously rotating shaft bymeans of a mechanism, such as a. clutch, which necessitates an individual operating means for each switch. Means have also to be provided whereby the motion of the wipers is arrestedwhen they have come into contact with the required contacts and to disconnect them from theti'nfiuen'ce of the rotating shaft. 7

These arrangements require individual apparatus to each switch and the present invention has in view arrangements whereby a great economy of apparatus is efiected and is specially though not solely applicable to the case of a group of switches where only one switch is required to drive at a'time.

In the present invention a'shaft, com1no'n to all the switches of a group, and which oscillates under the influence of the armature of an electromagnet, constitutes the power transmit-ting and driving means of the switches. Each switch is associated with its own pawl "or pawls attached to or operated on by the oscillating shaft, a pawl being adapted when the switch is required for use to engage with r a ratchetmechanismindividual to the switch.

' The pawls may be brought into engagementwith their respective ratchets by means of cams mounted on an auxiliary shaft rotated by a further electromagnet, the cams being arranged with their operating surfaces at clifferent angular pesitionswith respect to one another so that on rotation of the auxiliary shaft the pawls will be brought into engagement with their respective ratchets in turn. Normally the cams may hold the pawls out of engagement with'the'ratchets but the operation of the'further magnetcauses one of the cams to bring a'pawl into engagementwith its.

ratchetp The corresponding switch is then stepped by means of the pawl oscillated by the driving shaft and the stepping may be terminated by any suitable testing arrange- 0 ment. The auxiliary shaft may be returned to a normal position under the control of a special cam or other convenient device, and the switch recently stepped may be held if necessary by independent means. Should it berequired that more than one switch should be capable of being driven at a time, then individual means may be provided fer each switch which will bring the pawls of the switches to be used into engagement with their respective ratchet mechanisms, the

pawls being attached to or operated on by the common oscillating driving shaft.

WVhere stepping switches are used which have motion in two directions at right angles to one another in the same plane, each switch may be provided with twopawl and ratchet mechanisms, the two pawls being placed around the circumference of the shaft 90 apart and tangential thereto. Each set of pawls would have associated with it an auxiliary set of cams so that the correct pawl would engage its ratchet for the required motion of theswitch. During the first movement the first pawl only would engage with its ratchet mechanism and during the second movement only the second pawl with its ratchet mechanism. Ifmo're than one switch is required to be driven at a time then separate means for bringing the respective pawls into operation may be used. i For lightness the pawls may be of springy flexibie material similar to a clock spring,

thereby avoiding the'use of pivots.

sented by ratchet wheels R are mounted in a i me'Fthe position of the bank of contacts of the right-handswitch being indicated by a dotted semi-circle. The ratchet wheels are mounted onspindle rotating in suitable bearings in brackets secured to the framework,

which spindles also carry the switch Wip 100 This mounting is not shown in the dr: wing as the usual method of carrying such ratchet and wiper spindles in rotary stepping switches is well known and its inclusion would only complicate the drawing. At each end of the frame F are brackets BA and BB and near the right-hand end is a further bracket BC. In these brackets are journalled the shafts CMS and DMS. Shaft CMS ca ries a number of cams C, one for each switch in the frame, and shaft DMS has fixed to it a corresponding number of pawls P, of which all but one normally rest on the surface of the cams, which are adapted to engage the teeth of the ratchets R. Each cam C has a portion of its surface flattened as shown at CS, and the cams are so mounted on the shaft CMS that the flats CS occupy (litterent relative positions so that as the cam shaft is rotated each tlat comes in turn beneath a pawl allowing it to drop on to its ratchet wheel and enter a tooth as will be clearly seen in Fig. The pawls may be of springy material so as to be light and raised easily by the cams and may be suitably attached to a bracket attached to the shaft DMS. Only one pawl is thus engaged at a time the remaining pawls being raised from engagement with the ratchet wheels by means of the cams as will be seen in Fig. 3. The angular displacement of the flats on the cams is determined by the number of switches to be operated by the shaft and is so arranged that at each step of the shaft one cam allows a pawl to engage its ratchet wheel, the several pawls engaging their ratchets in turn as the shaft is rotated. At the end of the shaft CMS is mounted a ratchet wheel R'W engaged by a pawl PW attached to the armature of an electro-magnet CM which forms the driving mechanism for the cam shaft, the mechanism being so arranged that for each energization or de-energization of magnet CM the shaft CMS is rotated through an angle equal to the angular displacement of the flats CS on the cams C. An electromagnet DM is also suitably mounted in the frame and its armature is attached to the shaft DMS so as to oscillate it or partially rotate it at each energiza- 'tion and de-ener ization of the ma net. This action causes all the pawls to be advanced and retracted, the pawl engaging a ratchet R stepping the ratchet wheel at each oscillation f the shaft DMS.

The arrangements operate in the following manner when it is desired to use one of the switches for the purpose of set-ting up a connection.

Magnet CM is intermittently energized to rotate the cam shaft CMS until a pawl is engaged with a ratchet belonging to a switch. which is free for use or which has been marked for use. The circuit of magnet CM is then interrupted by suitable means which are controlled by contacts operated by the cam associated with the switch or by an associated cam and magnet DM is energized in a suitable manner by an interrupter to oscillate shaft DlMtS and rotate the ratchet wheel selected by means of the engaged pawl, thereby stepping the switch to a marked contact or until a free contact in a group is found, the operation of magnet DM being interrupted by a test relay in any suitable manner when such a contact is found.

A further cam may be provided on shaft CMS which may control contacts whereby on re-cnergization of the magnet CM after a switch has been set the shaft may be rotated to a normal position. Independent holding detents may be provided to engage the ratchets to hold them in a set position.

In Fig. 4t are shown circuit arrangements suitable for the control of a switch and a common driving means shown in Fig. 1.

In the upper part of Fig. 1': is shown a switch Rb having l wipers and associated contact banks and two relays designated T and TS. The. contacts CC are contacts closed by the cam C (or by an associated cam) when it is in the position shown in Fig. 2. In the lower part of Fig. 4 are shown the circuits for controlling the magnets CM and DM and for setting a two motion selector MS having 3 wipers which responds to dialled impulses and according to its setting selects a free outlet in a group of outlets and marks this outlet to be searched for by the switch RS.

Switch BS is marked selectable if the associated control circuit is free in which case battery will be connected over the resistance, contact m1. vertical off-normal contact 013 of switch MS. contact 251, relay T, contact 682 to the incoming test wire. W hen the switch is picked up relay T operates and by changing over its contact t1 operates relay X which by opening contact 951 guards the control circuit from seizure over inlets to other switches RS and marks these inlets as being nonselectable. Contacts t2 and 13 extend the wires 0 and 7) to the control circuit. When the connection has been switched through to the wires incoming on the left-hand side of the figure battery on wire 6 operates relay A. Contact a]. opens to guard the vertical magnet VM of switch MS and contact a2 connects earth on wire 0 over contacts ts2, t2 and n1 to slow releasing dialling relay D. Relay D operates and at contact (Z1 prepares a holding circuit for itself during impulsing. Contact (Z2 opens a point in the circuit of the rotary magnet RM of switch MS and closes a point in the circuit of Vertical magnet- VM. A further result of the operation of relay X is the closure of contacts 0:72 and Contact connects relay TC to the cam contacts CC of the individual switches RS and contact connects earth on wire 0 to magnet CM. The magnet is intermittently energized by means of the interrupter and rotates the cam shaft CMS until the cam contacts CC of theseized switch RS are closed whereupon contact t5 being closed relay TC operates. Contact tel disconnects magnet CM and prepares a circuit for magnet DM. The pawl associated with switch BS is brought into engagement with the ratchet consequent on the flat on the cam C coming beneath it and it is when a cam takes up such a position that the contacts CC are closed.

Dialled impulses of the train for controlling the setting of switch RS are received by relay A which repeats them at contact al to the magnet VM and the wipers of switch MS are stepped vertically. At the first step the vertical off-normal contactsnl, n2 and 723 are operated. During the impulse breaks relay D is held in a circuit over the frontof contact n1, contact (Z1, back of contact a2 to earth on wire 0. Contact n2'closes a point in the circuit of release magnet. ZM of switch MS and contact n3 opens a further point in the test in circuit. At the end of the impulse train relay D releases and cannot re-operate and on the falling back of contact (Z2 a circuit is closed from earth over contacts M2, (Z2, a2. a3, magnet RM, inter rupter to battery. Magnet RM operates and rotates the wipers of switch MS in search of a free outlet designated by the presence of battery potential on the outgoing test wire 0. When such is encountered relay TD operates by means of its winding (I) from this battery connection over the test wiper of switch MS. contact (12 to earth on the incoming test wire. The relay locks up over contact tdl and at contact hi2 opensthe magnet circuit bringing the switch to rest. Contact M3 connects earth directly to the test wiper of switch MS to mark the link engaged and contact tile disconnects relay A and completes an impulsing circuit over switch MS to the next switching stage to enable a succeeding switch to respond to the next train of impulses while switch BS is being set. Contact tdf) connects battery over a wiper of switch MS to mark the seized outlet in the bank of switch RS and contact tclti closes the circuit of magnet- DM over contacts #01, t3, t2, tsQ, wire 0 to earth. Magnet DM is now intermittentlyenergized by the interrupter and oscillates the shaft DMS (Fig. 1) whereby the pawl lowered by the cam associated. with switch RS causes the ratchet wheel of switch RS to be turned step by step whereby the wipers are rotated until they encounter the contacts marked by switch M S. \Vhen these contacts are reached relay TS operates from earth on the incoming wire a over its winding (I). contact t4 lower wiper of switch RS, middle wiper of switch MS contact M5 to battery. Relay TS locks up by means of its winding (II) circuit.

and switches the connection through at contacts as, ts4 "and 1685. Contact $82 opens the I circuit of magnet DM and of relays T and X and disconnects the holding earth from the control circuit. The above mentioned relays release, contact tat disconnectingwindiMS, its circuit being opened by the restoration of the vertical oil-normal contact n2 when the switchreaches'its normal position. Contact n8 closing the controlcircuit is again rendered available for use.

At the end of the conversation; earth is disconnected from wire 0 at the selector from which the release of the connection is con trolled and relay TS releases and at contact Z82 closes the test in wire to'the control I claim;

1. In a switching mechanism comprising a plurality of switches, an individual pawl and a cooperating individual ratchet for each of said switches, means for selecting any one of said pawls to operative-1y associate said selected pawl with its cooperating ratchet, and

means common to said switches for operating said pawls to elfect the movement of the ratchet cooperating with the selected pawl.

2. In a telephone system, a plurality of switches, an individual pawl and cooperating ratchet for each of said -switches, means responsive to the seizure of one of said switches for operatively connecting the pawl of said seized switch with its cooperating ratchet to prepare said switch for operation, and driving means common to said switches operated responsive to said last means for operating said seized switch by means of its individual pawl and ratchet.

3. In a switching mechanism, the combination of a plurality of switches, a shaft common to said switches, an individual pawl for each of said switches attached tosaid shaft, a ratchet individual to each switch for cooperating. with the corresponding. individual pawl, means for selecting any one of 7 said pawls to operativelv associate said pawl with its cooperating ratchet. and means common to said switches for oscillating'said shaft to operate said pawls to effect the movement of the ratchet cooperating with the selected pawl.

4. In a switching mechanism, the combination of a plurality of switches. a shaft common to said switches, an individual pawl for each of said switchesattached to said shaft, a ratchetindivid'ual to each switch for cooperating with the corresponding individual pawl, means forselecting any one of said pawls to operatively associate said pawl with itscooperating ratchet, and an intermittently energized electromagnet for oscillating said pawl shaft to operate said pawls to etiect move ment of the ratchet cooperating with the selected pawl.

5. In a switching mechanism comprising a plurality of switches, an individual pawl and a cooperating ratchet for each of said switches, a shaft common to said switches, cams mounted in staggered relation with respect to each other on said shaft, means for operating said shaft and cams to operatively associate one of said pawls with its cooperating ratchet, and means common to said switches for operating said pawls to effect movement of said ratchet operatively associated with said pawl.

6. In a switching mechanism comprising a plurality of switches, an individual pawl and a cooperating ratchet for each of said switches, a shaft common to said switches, cams mounted in staggered relation with respect to each other on said shaft, a pawl and ratchet mechanism, an intern'iittently energized clectromagnet for operating said pawl and ratchet mechanism to rotate said cam shaft and cams to operatively associate one of said pawls with its cooperating ratchet, and means common to said switches for operating said pawls to elfect movement of said ratchet operatively associated with said one pawl.

7. In a switching mechanism comprising a plurality of switches, a first shaft common to said switches, an individual pawl for each of said switches attached to said shaft, a ratchet individual to each of said switches for coopcrating with the corresponding individual pawl, a secou d shaft common to said switches, cams mounted in staggered relation with respect to each other on said second shaft, and means for operating said cam shaft to operatively associate one of said pawls with its cooperating ratchet.

8. In a switching mechanism comprising a plurality of switches, a first shaft common to said switches, an individual pawl for each of said switches attached to said shaft, a ratchet individual to each of said switches for cooperating with the corresponding individual pawl, a second sh aft common to said switches, cams mounted in staggered relation with respect to each other on said second shaft, means for operating said cam shaft to operatively associate one of said pawls with its cooperating ratchet, and means for oscillating said pawl shaft to operate said pawls to effect movement of said ratchet operatively associated with said pawl.

In a telephone system, a plurality of switches, a common. control circuit and individual control circuits for said switches, means including said common control circuit for preparing one of said switches for operation, means including the individual circuit of the prepared switch for seizing said switch,

an individual pawl and cooperating ratchet for each of said switches, means responsive to the seizure of said switch for operatively associating the individual pawl of the seized switch with its cooperating ratchet, and means common to said switches for operating said pawls to effect the operation of said seized switch by means of its individual pawl and ratchet.

10. In a telephone system, a plurality of switches, means for seizing one of said switches, a circuit individual to said seized switch prepared in response to said seizure, an individual pawl and a cooperating ratchet for each of said switches, means responsive to the seizure of said switch for operatively associating the individual pawl of the seized switch with its cooperating ratchet and for completing said prepared circuit, common driving means for operating said pawls, and means responsive to the comple tion of said circu for operating said common driving means to operate said switch by means of its individual pawl and ratchet.

11. la a telephone vstem. a plurality of switches, a circuit individual to each of said switches, an individual pawl and ratchet for ich of said switches, a rotating cam device, means for preparing one of said individual circuits in response to the seizure of one of said switches, means for rotating said cam device, cams on said device rotated therewith for successively and operatively engaging and disengaging each individual pawl to and from its associated ratchet, contacts associated with each cam closed at the time the corresponding individual pawl operatively engages its associated ratchet to complete each said individual circuit when prepared, and means operative in response to the completion of a prepared individual circuit for stopping the rotation of said device.

12. In a telephone system, a plurality of switches, a circuit individual to each of said switches, an individual pawl and ratchet for each of said switches, rotating cam device, means for preparing one of said individual circuits in response to the seizure of one of said switches, means for rotating said cam device, cams on said device rotated therewith for successively and operatively engaging and disengaging each individual pawl to and from its associated. ratchet, contacts associated with each cam clos d at the time the corresponding individual pawl operatively engages its associated ratchet to complete each said indiidual circuit when prepared, means operative in response to the completion of a prepared individual circuit for stopping the rotation of said device, and means for simultaneously operating all the pawls individual to all said switches to operate only the switch having its individual pawl in engagement with its associated ratchet.

18. In a telephone system, a plurality of switches, circuits individual to each of said switches, means for preparing one of said circuits in response to a call, driving means common to all of said switches also operated responsive to a call, contacts included in each said individual circuit successively closed by said driving means, means for stopping said driving means in response to the closure of the contacts completing said prepared individual circuit, and means common to said switches for thereafter operating the switch having its individual circuit completed.

14. In a telephone system, a plurality of switches, circuits individual to each of said switches, means for preparing one of said circuits in response to the seizure of one of said switches, driving means common to all said switches also operated responsive to said seizure for successively closing said individual circuits, means for stopping said driving means in response to the closure of said prepared circuit, a group of trunk lines, a switch common to said plurality of switches, means for operating said'common switch in 2 response to impulses to select an idle one of said trunk lines, means responsive thereto for marking the selected trunk line in the bank of said seized switch, and means common to said switches for thereafter operating the said seized switch in search of the marked trunk line.

15. In a telephone system, a plurality of switches, circuits individual to each of said switches, means for preparing one of said circuits in'response to the seizure of one of said switches, driving means common to all said switches also operated responsive to said seizure for successively closing said individual circuits, means for stopping said driv- 4 ing means in response to the closure of said prepared circuit, a group of trunk lines, a switch common to said plurality of switches, means for operating said common switch in response to impulses to select an idle one of 4 said trunk lines, means responsive thereto for marking the selected trunk line in the bank of said seized switch, means common to said switches for thereafter operating the said seized switch in search of the marked trunk.

line, and means for providing an impulsing circuit over said common switch to said trunk line during the searching movement of said seized switch.

In testimony whereof I afiix my signature.

DAVID ADAM CHRISTIAN. 

